Re: On the one hand
I didn't miss that part. But I suspect we differ about what a backdoor is. In my book, a backdoor is an unadvertised method of gaining access to a system remotely. Whether or not the credentials are hardcoded doesn't matter.
I may be misunderstanding what they're doing here, but my understanding is that the telnet interface is not remotely accessible by default. I'm also willing bet it's not undocumented.